add workflow and add script

.github/workflows/port-images-to-ghcr.yml

@@ -0,0 +1,22 @@
+on:
+  push:
+    branches:
+      - main
+
+name: Port docker official images to GHCR
+
+jobs:
+  port-images:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Login to GHCR (GitHub Packages)
+        uses: docker/login-action@v3
+        with:
+          registry: ghcr.io
+          username: ${{ github.actor }}
+          password: ${{ secrets.GITHUB_TOKEN }}
+
+      - name: Pull from Docker Hub, push to GHCR
+        run: ./port-images-to-ghcr

README.md

@@ -1 +1,7 @@
-# docker-official-images
+# Docker Official Images
+
+We are moving away from Docker Hub to GitHub Container Registry because of rate limiting issues. There may be certain images however, that officially available on Docker Hub so this is a small script to port those images to GHCR. You can then pull them using:
+
+```bash
+docker pull ghcr.io/mrc-ide/docker-official-images/<image-name>:<tag>
+```

port-images-to-ghcr

@@ -0,0 +1,14 @@
+#!/usr/bin/env bash
+set -ex
+
+declare -a docker_images=(
+    "redis:6"
+    "redis:5"
+)
+
+for image in "${docker_images[@]}"
+do
+    docker pull "$image"
+    docker image tag "$image" ghcr.io/mrc-ide/docker-official-images/"$image"
+    docker image push ghcr.io/mrc-ide/docker-official-images/"$image"
+done